Diagnostic Delays in Thoracic Cancer Care: A Data-Linkage, Cohort Study between Primary Care, Hospital, and Registry Data

Background: Nearly half of patients with thoracic cancer are diagnosed at a late stage, contributing to poor survival. This may be due to delays in diagnosis. Methods: This study established a longitudinal cohort by linking data between primary care, hospital, and registry datasets in the State of Victoria, Australia, and evaluated the diagnostic intervals (DIs) against the recommended time frames in the Australian Optimal Care Pathways (OCP) guidelines. The intervals included the DI, the time from the first presentation in primary care to cancer diagnosis at hospitals (OCP recommendation, 35 d); and the diagnostic and treatment interval (DTI), from the first presentation in primary care to cancer treatment initiation (OCP recommendation, 49 d). Results: A total of 268 patients diagnosed between 2005 and 2021 were linked and analyzed for DI, and 249 for DTI. Among them, 76% experienced diagnostic delay, with DI longer than the recommended 35 d; 86% experienced diagnostic and treatment delay, with DTI longer than the recommended 49 d. Multivariable logistic regression analyses found both diagnostic delays to be consistent across the observation period (P > 0.05). Diagnostic delay was associated with any comorbidity (odds ratio [OR] = 2.49 [95% confidence interval, 1.23 to 5.05]), existing respiratory disease (OR = 2.51 [1.30 to 4.83]), and stages I and II (OR = 3.89 [1.55 to 9.77]). Conclusion: This study demonstrates the feasibility of conducting research with linkage to primary care datasets in Australia. We demonstrated healthcare system delays, which may contribute to poorer thoracic cancer outcomes.